Simplified performance-based optimal seismic design of reinforced concrete frame buildings

摘要

This paper presents a simplified performance-based optimal seismic design approach for multi-story reinforced concrete moment frames. The proposed approach minimizes construction cost and takes member plastic rotation and optionally inter-story drift as optimization constraints. Other seismic design requirements reflecting successful design practice are also incorporated. Simplification is made by reducing design variables into two, one for overall system stiffness and the other for overall system strength. The optimization contains two stages, the determination of feasible region boundary in strength and stiffness domain and optimization in material consumption domain. Capacity spectrum method, which jointly considers nonlinear static analysis and inelastic design spectrum, is used to estimate the global and local deformation demands at peak dynamic response. The proposed optimization approach is applied to the design of a six-story reinforced concrete frame. The design results indicate that 30% of needed flexural strength and 26% of cross-sectional area can be reduced from the initial strength-based design. Nonlinear time-history analyses are conducted on the optimized structure using ten historical ground motions scaled to represent three levels of seismic hazard.